用Tkinter实时读取线程中的高频数据和绘图图

Question

在过去的几周里，我一直在尝试开发一个应用程序，它可以读取OpenBCI Cyton (@250Hz)的脑电图数据，并绘制一个“实时”的图形。这里似乎更好的是线程。我将找到的在这里1应用于与Tkinter通信线程，但应用程序仍然无法工作(给出错误RecursionError: maximum recursion depth exceeded while calling a Python object)。也许我做错了什么，因为我试图使用多个.py文件？请参阅下面我的代码的主要部分和上下文中的一些更多注释：

###FILE main.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-

from AppWindow import *

window = AppWindow()
window.start()

###FILE AppWindow.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import tkinter as tk
from tkinter import ttk
from tkinter.scrolledtext import ScrolledText
import scroller as scrl
import logging
import requests
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
import random
from pandas import DataFrame
import stream_lsl_eeg as leeg


#Definitions
H = 720
W = 1280
#Color palette>> https://www.color-hex.com/color-palette/92077
bg_color = "#c4ac93"
sc_color = "#bba58e"
tx_color = "#313843"
dt_color = "#987f62"
wn_color = "#6b553b"


class AppWindow:

    #Other Functions

    def plotGraph(self, x, y):
        self.ax.clear()
        self.ax.plot(x,y, color = tx_color)
        plt.subplots_adjust(bottom=0.31, left=0.136, top=0.9, right=0.99)
        plt.ylabel('Magnitude', fontsize = 9, color = tx_color)
        plt.xlabel('Freq', fontsize = 9, color = tx_color)
        self.figure.canvas.draw()

    def __init__(self):
        self.root = tk.Tk() #start of application
        self.root.wm_title("Hybrid BCI - SSVEP and Eye Tracker")

        #Other Graphical Elements

        #Button that calls function
        self.btn_ReceiveEEG = tk.Button(self.EEG_frame, text = "Receive EEG signal", bg = bg_color, fg = tx_color, state = tk.DISABLED, command = lambda: leeg.getEEGstream(self))
        self.btn_ReceiveEEG.place(anchor = 'nw', relx = 0.52, rely = 0.5, width = 196, height = 40)

        #Other Graphical Elements

    def start(self):
        self.root.mainloop() #end of application

### FILE stream_lsl_eeg.py
from pylsl import StreamInlet, resolve_stream
import tkinter as tk
import AppWindow as app
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import threading
import queue
import time


class myThread(threading.Thread):
    def __init__(self, name, q, f):
        threading.Thread.__init__(self)
        self.name = name
        self.q = q
        self.f = f

    def run(self):
        print("Starting ", self.name)
        pullSamples(self.q, self.f) #place where function is called


def getInlet(app): #this is triggered by another button and it's working fine
    global inlet
    app.logger.warn('Looking for an EEG strean...')
    streams = resolve_stream('type', 'EEG')
    inlet = StreamInlet(streams[0])
    app.logger.warn('Connected')
    app.btn_ReceiveEEG.config(state = tk.NORMAL)


def pullSamples(q):
    i = 0
    while i<1000:
        sample, timestamp = inlet.pull_sample()
        threadLock.acquire()    #thread locks to put info in the queue
        q.put([sample,timestamp]) #data is put in the queue for other threads to access
        threadLock.release()    #thread unlocks after info is in
        i += 1
    stopcollecting = 1
    print("Exit flag on")

def plotSamples(app, kounter): #Outside Thread
    if not stopcollecting: #testing if stream reception stopped
        while dataqueue.qsize(  ):
            try:
                kounter += 1
                sample, timestamp = dataqueue.get(0)
                samples.append(sample[0]) #getting just channel 1 (0)
                timestamps.append(timestamp)
                show_samples = samples[-250:]
                show_timestamps = timestamps[-250:]
                app.plotGraph(show_timestamps,show_samples)
                print(counter) #this was just a control to count if the right amount of samples was coming out of the queue
            except dataqueue.Empty:
                pass #still not implemented, but will return to the main application
        app.root.after(60, plotSamples(flag,app,kounter)) #60 chosen because plot should update every 15 samples (15/250 = 0,06s)   


def getEEGstream(app): #function called by button
    app.logger.warn('Starting thread...')
    #
    kounter = 0
    start = time.perf_counter()
    thread1.start()
    ##
    plotSamples(flag, app, kounter)
    ##
    thread1.join() #I don't know if I need this...
    finish = time.perf_counter()
    #
    print(f'Sizes: Samples [{len(samples)}, {len(samples[0])}], {len(timestamps)} timestamps')
    print(f'Sucessfully streamed in {round(finish-start,3)}s!')

###
threadLock = threading.Lock()
dataqueue = queue.Queue()
stopcollecting = 0
kounter = []
flag = queue.Queue() #secondary queue for flags not used at the moment
flag.put(0)
thread1 = myThread("Thread-1", dataqueue,flag)
samples,timestamps = [],[]
show_samples, show_timestamps = [],[]

正如我所发现的在这里2，函数不应该调用自己，但它基本上就是在这里1所做的。而且，我不认为我会多次调用root.mainloop()，就像在在这里3中那样。

执行后，python将给出以下错误/输出：

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\robotics\AppData\Local\Continuum\anaconda3\envs\psychopy\lib\tkinter\__init__.py", line 1705, in __call__
    return self.func(*args)
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\AppWindow.py", line 109, in <lambda>
    self.btn_ReceiveEEG = tk.Button(self.EEG_frame, text = "Receive EEG signal", bg = bg_color, fg = tx_color, state = tk.DISABLED, command = lambda: leeg.getEEGstream(self))
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\stream_lsl_eeg.py", line 118, in getEEGstream
    plotSamples(flag, app, kounter)
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\stream_lsl_eeg.py", line 104, in plotSamples
    app.root.after(60, plotSamples(flag,app,kounter))
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\stream_lsl_eeg.py", line 104, in plotSamples
    app.root.after(60, plotSamples(flag,app,kounter))
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\stream_lsl_eeg.py", line 104, in plotSamples
    app.root.after(60, plotSamples(flag,app,kounter))
  [Previous line repeated 986 more times]
  File "C:\Users\robotics\Documents\gitDocuments\SSVEP_EyeGaze_py\stream_lsl_eeg.py", line 92, in plotSamples
    while dataqueue.qsize(  ): # if not dataqueue.empty():
  File "C:\Users\robotics\AppData\Local\Continuum\anaconda3\envs\psychopy\lib\queue.py", line 87, in qsize
    with self.mutex:
RecursionError: maximum recursion depth exceeded while calling a Python object
Exit flag on

显然，这意味着线程正在成功执行，但是plotSamples()正在崩溃。

有什么建议吗？

Answer 1

after() (类似于按钮的command=和bind())需要函数的名称，没有()，没有参数--它被称为callback -- after将其发送给mainloop，mainloop随后使用()来运行它。

在()中使用函数

 app.root.after(60, plotSamples(flag,app,kounter))

因此它一次运行它(它不将它发送到mainloop)，并且这个函数再次运行--同一函数同时运行，相同的函数，等等--所以创建递归。

它的作用就像

 result = plotSamples(flag,app,kounter) # run at once
 app.root.after(60, result)

如果您必须在参数中使用函数，那么您可以

 app.root.after(60, plotSamples, flag, app, kounter)

最终，您可以使用lambda创建没有参数的函数。

 app.root.after(60, lambda:plotSamples(flag,app,kounter) )